CFD simulations in support of Shuttle Orbiter contingency abort aerodynamic database enhancement

Shuttle Orbiter Contingency Abort Aerodynamics, II: Real-Gas Effects and High Angles of Attack

“…The OADB was the basis for comparing, verifying and establishing the accuracy of the computed aerodynamic characteristics for the run matrix, and experimentally measured pressure coefficients were the basis for the benchmark case. The details of the process and methodology followed at NASA Ames Research Center, plus a complete set of results, are given in the comprehensive paper of Papadopoulos et al [3] At the start of the previous project it was expected that, apart from the effort involved in generating complex volume grids for various angles of attack and control surface settings, the work would be fairly routine -involving straightforward application of mature CFD tools to the various flight cases and extraction of pressure and shear loads for structural analysis. However, the results from the Mach 15 computations yielded a few surprises.…”

“…The strategy adopted in the present work is to compute a large number of cases in the hypersonic regime with both ideal-and real-gas models using coarsened versions of volume grids that were used in the previous computations [3]. The results of the ideal-gas computations are compared against experimental data wherever possible.…”

“…Figure 2 shows the Orbiter configuration, the coordinate system, and sign conventions for the positive aerodynamic forces (C N and C A ) and the pitching moment (C m ), used in the present work. Note that there are no engine details in the aft section of the vehicle and the engines have been covered [3]. This simplification to the vehicle configuration prevents excessive complexity in the three-dimensional volume grid topology.…”

“…Version 3.2.4 of the commercially available code, GASPex [6] developed by AeroSoft, Inc., is used in all of the simulations performed in the present work. This CFD code was also used in the earlier work of Papadopoulos et al [3] Information about the physical and numerical modeling options exercised in GASPex is summarized in Table 1. The choice of numerical algorithm is based on the experience gained from previous projects [7,8].…”

“…2. No new grids -generation of three-dimensional volume grids of the complexity used in the work of Papadopoulos et al [3] was a time-consuming effort. Re-use of the existing volume grids represents substantial savings in time.…”